Modified conjugated diene-based polymer and method for preparing the same

ABSTRACT

The present invention relates to a modified conjugated diene-based polymer, and more particularly, provides a modified conjugated diene-based polymer including a functional group derived from a modifier including a compound represented by Formula 1, and a method for preparing the same.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of priority based on Korean Patent Application No. 10-2016-0151387, filed on Nov. 14, 2016, the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a modifier, and more particularly, to a modifier making excellent interaction of a rubber polymer with an inorganic filler, a method for preparing the same, and a modified conjugated diene-based polymer including a functional group derived from the modifier and has good processability and excellent tensile strength, abrasion resistance and wet skid resistance.

BACKGROUND ART

According to the recent demand for cars having a low fuel consumption ratio, a conjugated diene-based polymer having modulational stability represented by wet skid resistance as well as low rolling resistance, and excellent abrasion resistance and tensile properties is required as a rubber material for tires.

In order to reduce the rolling resistance of tires, there is a method of reducing hysteresis loss of vulcanized rubber, and rebound resilience at 50° C. to 80° C., tan δ, Goodrich heating, or the like is used as an evaluation index of the vulcanized rubber. That is, it is desirable to use a rubber material having high rebound resilience at the above temperature or a low tan δ value or Goodrich heating.

Natural rubbers, polyisoprene rubbers, or polybutadiene rubbers are known as rubber materials having low hysteresis loss, but these rubbers have a limitation of low wet skid resistance. Thus, recently, modified conjugated diene-based polymers or copolymers such as styrene-butadiene rubbers (hereinafter, referred to as “SBR”) and butadiene rubbers (hereinafter, referred to as “BR”), are prepared by emulsion polymerization or solution polymerization to be used as rubbers for tires. Among these polymerization methods, the greatest advantage of the solution polymerization in comparison to the emulsion polymerization is that the vinyl structure content and the styrene content, which specify physical properties of the rubber, may be arbitrarily adjusted and its molecular weight and physical properties may be controlled by coupling or modification. Thus, the SBR prepared by the solution polymerization is widely used as a rubber material for tires because it is easy to change a structure of the finally prepared SBR or BR, and movement of chain terminals may be reduced and a coupling force with a filler such as silica and carbon black may be increased by coupling or modification of the chain terminals.

If the solution-polymerized SBR is used as the rubber material for tires, since a glass transition temperature of the rubber is increased by increasing the vinyl content in the SBR, physical properties such as running resistance and braking force, required for tires may be controlled, and fuel consumption may also be reduced by appropriately adjusting the glass transition temperature. The solution-polymerized SBR is prepared by using an anionic polymerization initiator and is being used by coupling or modifying the chain terminals of the polymer thus formed using various modifiers. For example, U.S. Pat. No. 4,397,994 discloses a method of coupling active anions of the chain terminals of a polymer obtained by polymerizing styrene-butadiene using alkyllithium which is a monofunctional initiator in a non-polar solvent, using a binder such as a tin compound.

Meanwhile, carbon black and silica are being used as a reinforcing filler of a tire tread, wherein, if the silica is used as the reinforcing filler, low hysteresis loss and wet skid resistance may be improved. However, since the silica having a hydrophilic surface has a low affinity with a rubber in comparison to the carbon black having a hydrophobic surface, dispersibility may be poor, and thus, there is a need to use a separate silane coupling agent to improve the dispersibility or provide coupling between the silica and the rubber. Therefore, attempt of introducing a functional group having affinity or reactivity with silica into the terminal of a rubber molecule is being performed, but its effect is insufficient.

DISCLOSURE OF THE INVENTION Technical Problem

The present invention has been devised to solve the above-mentioned problems of the conventional technique, and an object of the present invention is to provide a modified conjugated diene-based polymer which is modified from a modifier which makes excellent interaction with an inorganic filler when mixed therewith and has good processability and excellent tensile strength, abrasion resistance and wet skid resistance, and a method for preparing the same.

Technical Solution

To solve the above-described tasks, according to an embodiment of the present invention, there is provided a modified conjugated diene-based polymer including a functional group derived from a modifier which includes a compound represented by the following Formula 1:

In Formula 1, X¹ and X² may be each independently an N atom or CR⁷, where one or more of X¹ and X² may be required to be N atoms, R¹ to R⁴ may be each independently a divalent hydrocarbon group of 1 to 30 carbon atoms, or a heteroalkylene group of 1 to 30 carbon atoms, which includes one or more heteroatoms selected from the group consisting of N, O and S atoms, R⁵ and R⁶ may be each independently a monovalent hydrocarbon group of 1 to 30 carbon atoms, a heteroalkyl group of 1 to 30 carbon atoms, which includes one or more heteroatoms selected from the group consisting of N, O and S atoms, or a heterocycle of 1 to 30 carbon atoms, which includes one or more heteroatoms selected from the group consisting of N, O and S atoms, and R⁷ may be a hydrogen atom, a monovalent hydrocarbon group of 1 to 30 carbon atoms, a heteroalkyl group of 1 to 30 carbon atoms, which includes one or more heteroatoms selected from the group consisting of N, O and S atoms, or a heterocycle of 1 to 30 carbon atoms, which includes one or more heteroatoms selected from the group consisting of N, O and S atoms.

In addition, the present invention provides a method for preparing a modified conjugated diene-based polymer, including a step of polymerizing conjugated diene-based monomers, or a conjugated diene-based monomer and an aromatic vinyl-based monomer, in a hydrocarbon solvent including an organometal compound, to prepare an active polymer (S1); and a step of reacting or coupling the active polymer prepared in step (S1) with a modifier including a compound represented by the following Formula 1 (S2):

In Formula 1, the definition of each substituent is the same as defined above.

In addition, the present invention provides a modifier including the compound represented by Formula 1.

Advantageous Effects

According to the present invention, if a conjugated diene-based polymer is modified with a modifier making excellent interaction with an inorganic filler when mixed therewith, a functional group derived from the modifier is included in one terminal of the polymer, and thus, the preparation of a modified conjugated diene-based polymer making excellent interaction between a polymer and an inorganic filler is possible, and the modified conjugated diene-based polymer thus prepared has effects of good processability and excellent tensile strength, abrasion resistance and wet skid resistance.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described in more detail in order to assist the understanding of the present invention.

It will be understood that words or terms used in the description and claims of the present invention shall not be interpreted as the meaning defined in commonly used dictionaries. It will be further understood that the words or terms should be interpreted as having a meaning that is consistent with their meaning of the technical idea of the invention, based on the principle that an inventor may properly define the meaning of the words or terms to best explain the invention.

The modified conjugated diene-based polymer according to the present invention includes a repeating unit derived from a conjugated diene-based monomer, and a functional group derived from a modifier which includes a compound represented by the following Formula 1, at one terminal:

In Formula 1, X¹ and X² may be each independently an N atom or CR⁷, where one or more of X¹ and X² may be required to be N atoms, R¹ to R⁴ may be each independently a divalent hydrocarbon group of 1 to 30 carbon atoms, or a heteroalkylene group of 1 to 30 carbon atoms, which includes one or more heteroatoms selected from the group consisting of N, O and S atoms, R⁵ and R⁶ may be each independently a monovalent hydrocarbon group of 1 to 30 carbon atoms, a heteroalkyl group of 1 to 30 carbon atoms, which includes one or more heteroatoms selected from the group consisting of N, O and S atoms, or a heterocycle of 1 to 30 carbon atoms, which includes one or more heteroatoms selected from the group consisting of N, O and S atoms, and R⁷ may be a hydrogen atom, a monovalent hydrocarbon group of 1 to 30 carbon atoms, a heteroalkyl group of 1 to 30 carbon atoms, which includes one or more heteroatoms selected from the group consisting of N, O and S atoms, or a heterocycle of 1 to 30 carbon atoms, which includes one or more heteroatoms selected from the group consisting of N, O and S atoms.

In a particular embodiment, in Formula 1, X¹ and X² may be N atoms, R¹ to R⁴ may be each independently a divalent hydrocarbon group of 1 to 10 carbon atoms, and R⁵ and R⁶ may be each independently a monovalent hydrocarbon group of 1 to 10 carbon atoms.

In the present invention, the term “monovalent hydrocarbon group” may mean a monovalent atomic group in which carbon and hydrogen are bonded, such as a monovalent alkyl group, alkenyl group, alkynyl group, cycloalkyl group, cycloalkyl group including one or more unsaturated bonds, and aryl group.

In the present invention, the term “divalent hydrocarbon group” may mean a divalent atomic group in which carbon and hydrogen are bonded, such as a divalent alkylene group, alkenylene group, alkynylene group, cycloalkylene group, cycloalkylene group including one or more unsaturated bonds, and arylene group.

According to an embodiment of the present invention, the compound represented by Formula 1 may be a compound represented by the following Formula 1-1 or 1-2:

In Formulae 1-1 and 1-2, Me is a methyl group and Et is an ethyl group.

Meanwhile, the modified conjugated diene-based polymer may include a functional group derived from a modifier including a compound represented by Formula 1 above, at one terminal, and a functional group derived from a modification initiator which includes a compound represented by the following Formula 2, at the other terminal:

In Formula 2, R⁸ and R⁹ may be each independently one selected from the group consisting of an alkyl group of 1 to 20 carbon atoms, a cycloalkyl group of 3 to 20 carbon atoms, and an aralkyl group of 5 to 20 carbon atoms, or R⁸ and R⁹ may be combined with each other to form a saturated or unsaturated cyclic structure of 5 to 20 carbon atoms together with an adjacent N atom, where if R⁸ and R⁹ form a cyclic structure, a branched structure may be obtained, R¹⁰ may be a single bond, an alkylene group of 1 to 20 carbon atoms, or one linker selected from the group consisting of the following Formula 3 to Formula 5, and M may be an alkali metal:

In a particular embodiment, in Formula 2, R⁸ and R⁹ may be each independently one selected from the group consisting of an alkyl group of 1 to 12 carbon atoms, a cycloalkyl group of 3 to 14 carbon atoms, and an aralkyl group of 5 to 20 carbon atoms, R¹⁰ may be a single bond, an alkylene group of 1 to 20 carbon atoms, or one linker selected from the group consisting of Formula 3 to Formula 5 above, and M may be an alkali metal.

In a more particular embodiment, in Formula 2, R⁸ and R⁹ may be each independently methyl, ethyl, propyl, butyl, octyl, cyclopropyl, cyclohexyl, 3-phenyl-1-propyl, isobutyl, decyl, heptyl or phenyl, R¹⁰ may be a single bond, an alkylene group of 2 to 16 carbon atoms, or one linker selected from the group consisting of Formula 3 to Formula 5 above, and M may be Li.

If a modification initiator is used as a polymerization initiator for initiating the polymerization of a conjugated diene-based polymer, the functional group derived from a modification initiator including the compound represented by Formula 2 may mean a functional group in a polymer, which is positioned at one terminal of a conjugated diene-based polymer and correspondent to a polymerization initiation part, and may achieve effects of increasing mechanical properties such as rolling resistance and wet skid resistance as well as improving the dispersibility and processability of a conjugated diene-based polymer.

The repeating unit derived from the conjugated diene-based monomer may mean a repeating unit formed by the conjugated diene-based monomer during polymerization, and the conjugated diene-based monomer may be, for example, one or more selected from the group consisting of 1,3-butadiene, 2,3-dimethyl-1,3-butadiene, piperylene, 3-butyl-1,3-octadiene, isoprene, 2-phenyl-1,3-butadiene, and 2-halo-1,3-butadiene (halo means halogen atom).

Meanwhile, a modified conjugated diene-based copolymer may be, for example, a copolymer further including a repeating unit derived from an aromatic vinyl monomer together with the repeating unit derived from the conjugated diene-based monomer.

The repeating unit derived from the aromatic vinyl monomer may mean a repeating unit formed by an aromatic vinyl monomer during polymerization, and the aromatic vinyl monomer may include, for example, one or more selected from the group consisting of styrene, α-methylstyrene, 3-methylstyrene, 4-methylstyrene, 4-propylstyrene, 1-vinylnaphthalene, 4-cyclohexylstyrene, 4-(p-methylphenyl)styrene, and 1-vinyl-5-hexylnaphthalene.

If the modified conjugated diene-based polymer is a copolymer including a repeating unit derived from an aromatic vinyl monomer, the modified conjugated diene-based polymer may include the repeating unit derived from the conjugated diene-based monomer in an amount of 50 to 95 wt %, 55 to 90 wt %, or 60 to 90 wt %, and the repeating unit derived from the aromatic vinyl monomer in an amount of 5 to 50 wt %, 10 to 45 wt %, or 10 to 40 wt %, and within the ranges, effects of excellent rolling resistance, wet skid resistance and abrasion resistance may be achieved.

According to an embodiment of the present invention, the copolymer may be a random copolymer, and in this case, effect of excellent balance between physical properties may be achieved. The random copolymer may mean repeating units which constitutes a copolymer, arranged in disorder.

The modified conjugated diene-based polymer according to an embodiment of the present invention may have a number average molecular weight (Mn) of 10,000 g/mol to 2,000,000 g/mol, 50,000 g/mol to 1,000,000 g/mol, 100,000 g/mol to 500,000 g/mol, or 200,000 g/mol to 300,000 g/mol, and a weight average molecular weight (Mw) of 10,000 g/mol to 5,000,000 g/mol, 100,000 g/mol to 3,000,000 g/mol, 500,000 g/mol to 2,000,000 g/mol, or 800,000 g/mol to 1,000,000 g/mol, and within the ranges, effects of excellent rolling resistance and wet skid resistance may be achieved. In another embodiment, the modified conjugated diene-based polymer may have molecular weight distribution (Mw/Mn) of 1 to 5, 1.5 to 3, or 2 to 2.5, and within this range, effect of excellent balance between physical properties may be achieved.

In another embodiment, the modified conjugated diene-based polymer may have mooney viscosity of 40 to 110, 50 to 100, or 70 to 80 at 100° C., and within this range, effects of excellent processability and productivity may be achieved.

In addition, the modified conjugated diene-based polymer may have a vinyl content of 5 wt % or more, 10 wt % or more, or 10 wt % to 50 wt %, and within this range, the glass transition temperature may be adjusted in an appropriate range, and effects of excellent rolling resistance, wet skid resistance and a low fuel consumption ratio may be achieved. Here, the vinyl content may mean the amount of not 1,4-added but 1,2-added conjugated diene-based monomer based on 100 wt % of a conjugated diene-based copolymer composed of a monomer having a vinyl group and an aromatic vinyl-based monomer.

Meanwhile, the term “derived repeating unit” and “derived functional group” in the present invention may represent a component or a structure comes from a certain material, or the material itself.

A method for preparing a modified conjugated diene-based polymer according to the present invention may include a step of polymerizing conjugated diene-based monomers, or an aromatic vinyl-based monomer and a conjugated diene-based monomer, in a hydrocarbon solvent including an organometal compound, to prepare an active polymer which is coupled with an organometal (S1); and a step of reacting the active polymer and a modifier including a compound represented by the following Formula 1 (S2):

The definition of each substituent of Formula 1 is the same as defined above.

The hydrocarbon solvent is not specifically limited, but may be, for example, one or more selected from the group consisting of n-pentane, n-hexane, n-heptane, isooctane, cyclohexane, toluene, benzene and xylene.

According to an embodiment of the present invention, the compound represented by Formula 1 may be used in an amount of 0.01 mmol to 10 mmol based on total 100 g of the monomers.

According to an embodiment of the present invention, the organometal compound may be used in 0.01 mmol to 10 mmol, 0.05 mmol to 5 mmol, 0.1 mmol to 2 mmol, or 0.1 mmol to 1 mmol based on total 100 g of the monomers.

The organometal compound may be, for example, one or more selected from the group consisting of methyllithium, ethyllithium, propyllithium, n-butyllithium, s-butyllithium, t-butyllithium, hexyllithium, n-decyllithium, t-octyllithium, phenyllithium, 1-naphthyl lithium, n-eicosyl lithium, 4-butylphenyl lithium, 4-tolyl lithium, cyclohexyl lithium, 3,5-di-n-heptylcyclohexyl lithium, 4-cyclopentyl lithium, naphthyl sodium, naphthyl potassium, lithium alkoxide, sodium alkoxide, potassium alkoxide, lithium sulfonate, sodium sulfonate, potassium sulfonate, lithium amide, sodium amide, potassium amide, and lithium isopropylamide.

In addition, instead of the organometal compound, a modification initiator including a compound represented by the following Formula 2 may be used, and in this case, both terminals of the modified conjugated diene-based polymer thus prepared are modified and effect of maximizing affinity with an inorganic filler may be achieved.

In Formula 2, the definition of each substituent is the same as defined above.

Meanwhile, the polymerization of step (S1) may be performed by including a polar additive, and the polar additive may be added in an amount of 0.001 g to 50 g, 0.001 g to 10 g, or 0.005 g to 0.1 g based on total 100 g of the monomers. In addition, the polar additive may be one or more selected from the group consisting of tetrahydrofuran, ditetrahydrofurylpropane, diethyl ether, cycloamyl ether, dipropyl ether, ethylene methyl ether, ethylene dimethyl ether, diethyl glycol, dimethyl ether, tert-butoxy ethoxy ethane, bis(3-dimethylaminoethyl) ether, (dimethylaminoethyl) ethyl ether, trimethylamine, triethylamine, tripropylamine, and tetramethylethylenediamine, preferably, triethylamine or tetramethylethylenediamine, and may be the same as or different from a polar additive which may be injected during preparing the aminosilane-based compound. If the polar additive is included and conjugated diene-based monomers, or a conjugated diene-based monomer and an aromatic vinyl-based monomer are copolymerized, the reaction rates thereof may be compensated, and effect of inducing the easy formation of a random copolymer may be achieved.

The polymerization of step (S1) may be, for example, an anionic polymerization, and particularly, a living anionic polymerization by which an anionic active part is formed at the polymerization terminal through a propagation reaction by anions. In addition, the polymerization of step (S1) may be a polymerization with heating, an isothermal polymerization, or a polymerization at a constant temperature (adiabatic polymerization). The polymerization at a constant temperature means a polymerization method including a step of polymerizing using self-generated heat of reaction without optionally applying heat after adding an organometal compound, and the polymerization with heating means a polymerization method including injecting the organometal compound and then, increasing the temperature by optionally applying heat. The isothermal polymerization means a polymerization method by which the temperature of a polymer is kept constant by increasing heat by applying heat or taking heat after adding the organometal compound. In addition, the polymerization of step (S1) may be conducted in a temperature range of −20° C. to 200° C., 0° C. to 150° C., or 10° C. to 120° C.

The active polymer prepared by step (S1) may mean a polymer in which a polymer anion and an organometallic cation are coupled.

According to an embodiment of the present invention, the molar ratio of the modifier including the compound represented by Formula 1 and the organometal compound may be from 1:0.1 to 1:10, and within this range, modification reaction may be performed with optimal performance, and a conjugated diene-based polymer with a high modification ratio may be obtained.

The reaction of step (S2) is modification reaction for introducing the functional group derived from the modifier into an active polymer, and may be performed at 0° C. to 90° C. for 1 minute to 5 hours.

In addition, according to an embodiment of the present invention, the method for preparing a modified conjugated diene-based polymer may be performed by a batch type polymerization method or a continuous type polymerization method including one or more reactors.

The method for preparing a modified conjugated diene-based polymer may further include, for example, one or more steps among recovering and drying steps of a solvent and an unreacted monomer after step (S2) of the present invention according to need.

A modifier according to the present invention may include a compound represented by the following Formula 1:

In Formula 1, the definition on each substituent is the same as defined above.

The modifier of the present invention includes a compound containing a glycidol group in a molecule, and makes excellent interaction with an inorganic filler, specifically, a silica-based filler, and accordingly, effect of increasing dispersibility between a polymer modified from the modifier and a filler may be achieved.

According to the present invention, a rubber composition including the modified conjugated diene-based polymer is provided.

The rubber composition may include the modified conjugated diene-based polymer in an amount of 0.1 wt % or more, 10 wt % to 100 wt %, or 20 wt % to 90 wt %. Within the range, effects of excellent mechanical properties such as tensile strength and abrasion resistance, and excellent balance between each of physical properties may be achieved.

In addition, the rubber composition may further include other rubber components, if necessary, in addition to the modified and conjugated diene-based polymer, and, in this case, the rubber component may be included in an amount of 90 wt % or less based on the total weight of the rubber composition. Particularly, the other rubber components may be included in an amount of 1 part by weight to 900 parts by weight based on 100 parts by weight of the modified and conjugated diene-based copolymer.

The rubber component may be, for example, a natural rubber or a synthetic rubber, particularly, a natural rubber (NR) including cis-1,4-polyisoprene; a modified natural rubber which is obtained by modifying or purifying a common natural rubber, such as an epoxidized natural rubber (ENR), a deproteinized natural rubber (DPNR), and a hydrogenated natural rubber; and a synthetic rubber such as a styrene-butadiene copolymer (SBR), a polybutadiene (BR), a polyisoprene (IR), a butyl rubber (IIR), an ethylene-propylene copolymer, a polyisobutylene-co-isoprene, a neoprene, a polyethylene-co-propylene), a poly(styrene-co-butadiene), a poly(styrene-co-isoprene), a poly(styrene-co-isoprene-co-butadiene), a poly(isoprene-co-butadiene), a poly(ethylene-co-propylene-co-diene), a polysulfide rubber, an acryl rubber, a urethane rubber, a silicone rubber, an epichlorohydrin rubber, a butyl rubber, and a halogenated butyl rubber, and any one or a mixture of two or more thereof may be used.

The rubber composition may, for example, include 0.1 parts by weight to 200 parts by weight, 0.1 parts by weight to 150 parts by weight, or 10 parts by weight to 120 parts by weight of a filler based on 100 parts by weight of the modified conjugated diene-based polymer of the present invention. The filler may particularly be, for example, a silica-based filler, particularly, wet silica (hydrated silicate), dry silica (anhydrous silicate), calcium silicate, aluminum silicate, or colloid silica. Preferably, the filler may be wet silica which has the most significant compatible effect of improving effect of destruction characteristics and wet grip. In addition, the rubber composition may further include a carbon black-based filler, if needed.

In another embodiment, if silica is used as the filler, a silane coupling agent for the improvement of reinforcing and low exothermic properties may be used together. Particular examples of the silane coupling agent may include bis(3-triethoxysilylpropyl)tetrasulfide, bis(3-triethoxysilylpropyl)trisulfide, bis(3-triethoxysilylpropyl)disulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyltetrasulfide, 3-triethoxysilylpropyl-N,N-dimethylthiocarbamoyltetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyltetrasulfide, 3-trimethoxysilylpropylbenzothiazolyltetrasulfide, 3-triethoxysilylpropylbenzolyltetrasulfide, 3-triethoxysilylpropylmethacrylatemonosulfide, 3-trimethoxysilylpropylmethacrylatemonosulfide, bis(3-diethoxymethylsilylpropyl)tetrasulfide, 3-mercaptopropyldimethoxymethylsilane, dimethoxymethylsilylpropyl-N,N-dimethylthiocarbamoyltetrasulfide, or dimethoxymethylsilylpropylbenzothiazolyltetrasulfide, and any one or a mixture of two or more thereof may be used. Preferably, the silane coupling agent may be bis(3-triethoxysilylpropyl)polysulfide or 3-trimethoxysilylpropylbenzothiazyltetrasulfide in consideration of the improving effect of reinforcing properties.

In addition, in the rubber composition according to an embodiment of the present invention, a modified conjugated diene-based polymer in which a functional group having high affinity with silica is introduced into an active part as a rubber component is used, and the mixing amount of a silane coupling agent may be smaller than a common case.

Accordingly, the silane coupling agent may be used in an amount of 1 part by weight to 20 parts by weight, or 5 parts by weight to 15 parts by weight based on 100 parts by weight of silica, and within this range, effect as a coupling agent may be sufficiently exhibited, and the gelation of the rubber component may be prevented.

The rubber composition according to an embodiment of the present invention may be sulfur crosslinkable, and may further include a vulcanizing agent. The vulcanizing agent may particularly be a sulfur powder and may be included in an amount of 0.1 parts by weight to 10 parts by weight based on 100 parts by weight of a rubber component. With the amount in the above range, elasticity and strength required for a vulcanized rubber composition may be secured, and at the same time, a low fuel consumption ratio may be excellent.

The rubber composition according to an embodiment of the present invention may further include various additives used in a common rubber industry in addition to the above-described components, particularly, a vulcanization accelerator, a process oil, a plasticizer, an antiaging agent, a scorch preventing agent, a zinc white, stearic acid, a thermosetting resin, or a thermoplastic resin.

The vulcanization accelerator may use, for example, thiazole-based compounds such as 2-mercaptobenzothiazole (M), dibenzothiazyldisulfide (DM), and N-cyclohexyl-2-benzothiazylsulfenamide (CZ), or guanidine-based compounds such as diphenylguanidine (DPG), and may be included in an amount of 0.1 parts by weight to 5 parts by weight based on 100 parts by weight of the rubber component.

The process oil acts as a softener in a rubber composition and may include, for example, a paraffin-based, naphthene-based, or aromatic compound, and an aromatic process oil may be used in consideration of tensile strength and abrasion resistance, and a naphthene-based or paraffin-based process oil may be used in consideration of hysteresis loss and properties at a low temperature. The process oil may be included, for example, in an amount of 100 parts by weight or less based on 100 parts by weight of the rubber component. With the amount in the above-described range, the deterioration of tensile strength and low exothermic properties (low fuel consumption ratio) of the vulcanized rubber may be prevented.

The antiaging agent may include, for example, N-isopropyl-N′-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine, 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline, or a condensate of diphenylamine and acetone at a high temperature, and may used in an amount of 0.1 parts by weight to 6 parts by weight based on 100 parts by weight of the rubber component.

The rubber composition according to an embodiment of the present invention may be obtained by mulling using a mulling apparatus such as a banbury mixer, a roll, and an internal mixer according to mixing prescription. In addition, a rubber composition having low exothermic properties and good abrasion resistance may be obtained by a vulcanization process after a molding process.

Therefore, the rubber composition may be useful to the manufacture each member for tires such as a tire tread, an under tread, a side wall, a carcass coating rubber, a belt coating rubber, a bead filler, a chafer, and a bead coating rubber, or to the manufacture of rubber products in various industries such as a dustproof rubber, a belt conveyor, and a hose.

Also, the present invention provides a tire manufactured using the rubber composition.

The tire may include a tire or a tire tread.

Hereinafter, the present invention will be explained in more detail referring to embodiments. However, the following embodiments are only for the illustration of the present invention, and the scope of the present invention is not limited thereto.

EXAMPLES Example 1

To a 20 L autoclave reactor, 270 g of styrene, 710 g of 1,3-butadiene, 5,000 g of n-hexane, and 0.86 g of 2,2-di(2-tetrahydrofuryl)propane (DTP) as a polar additive were added, and the internal temperature of the reactor was elevated to 40° C. Then, 10 mmol of n-butyllithium was injected into the reactor, and an adiabatic reaction with heating was performed. After about 20 minutes from the completion of the adiabatic reaction with heating, 20 g of 1,3-butadiene was injected for capping the terminal of a polymer with butadiene. After 5 minutes, 0.5 g (5 mmol) of a compound represented by Formula 1-1 below was injected, and the reaction was performed for 15 minutes. Then, the polymerization reaction was quenched using ethanol, and 45 ml of a solution in which butylated hydroxytoluene (BHT) was dissolved in hexane as an antioxidant by 0.3 wt %, was added thereto. The polymer thus obtained was added to hot water heated using steam and stirred to remove solvents, followed by roll drying to remove remaining solvents and water to prepare a modified conjugated diene-based polymer. Analysis results on the modified conjugated diene-based polymer thus prepared are listed in Table 1 below.

Example 2

The same method as in Example 1 was conducted except for injecting 0.5 g (5 mmol) of a compound represented by Formula 1-2 below instead of the compound represented by Formula 1-1 in Example 1.

Comparative Example 1

The same method as in Example 1 was conducted except for not injecting the compound represented by Formula 1-1 in Example 1.

Comparative Example 2

The same method as in Example 1 was conducted except for injecting 0.5 g (5 mmol) of a compound represented by Formula 6 below instead of the compound represented by Formula 1-1 in Example 1.

Experimental Examples

Experimental Example 1

With respect to each of modified or unmodified conjugated diene-based polymers prepared in the examples and comparative examples, a weight average molecular weight (Mw, x10³ g/mol), a number average molecular weight (Mn, x10³ g/mol), molecular weight distribution (MWD), and mooney viscosity (MV) were measured. The results are listed in Table 1 below.

The weight average molecular weight (Mw, x10³ g/mol), and the number average molecular weight (Mn, x10³ g/mol) were measured by gel permeation chromatography (GPC) analysis, and the molecular weight distribution (MWD, Mw/Mn) was obtained by the calculation from each of the measured molecular weights. Particularly, GPC was conducted using two columns of PLgel Olexis (Polymer Laboratories Co. Ltd.) and one column of PLgel mixed-C (Polymer Laboratories Co. Ltd.) in combination, newly replaced columns were all mixed bed type columns, and polystyrene (PS) was used as a GPC standard material for calculating the molecular weights.

The mooney viscosity (MV, (ML1+4, @100° C.) MU) was measured by using MV-2000 (ALPHA Technologies Co., Ltd.) using Large Rotor at a rotor speed of 2±0.02 rpm at 100° C. In this case, a specimen used was stood at room temperature (23±3° C.) for 30 minutes or more, and 27±3 g of the specimen was collected and put in a die cavity, and then, Platen was operated for measurement for 4 minutes.

TABLE 1 Example Comparative Example Division 1 2 1 2 Mw 630 620 450 580 Mn 384 390 280 370 MWD 1.42 1.52 1.38 1.55 MV 72 70 58 68

Experimental Example 2

In order to comparatively analyze the physical properties of a rubber composition including each of modified or unmodified conjugated diene-based copolymers prepared in the examples and comparative examples and a molded article manufactured therefrom, tensile properties, abrasion resistance and wet skid resistance were measured, respectively, and the results are listed in Table 3 below.

1) Preparation of Rubber Specimen

By using each of modified or unmodified conjugated diene-based copolymers prepared in the examples and comparative examples as a raw rubber, mixing was performed according to the mixing conditions shown in Table 2 below. The raw material in Table 2 is represented by parts by weight based on 100 parts by weight of rubber.

TABLE 2 Amount Division Raw material (parts by weight) First stage Rubber 100 mulling Silica 70 Coupling agent 11.2 Process oil 33.75 Zinc white 3.0 Stearic acid 2.0 Antioxidant 2.0 Antiaging agent 2.0 Wax 1.0 Rubber accelerator 1.75 Second stage Sulfur 1.5 mulling Vulcanization accelerator 1.5

Particularly, the rubber specimen was mulled via a first stage mulling and a second stage mulling. In the first stage mulling, a raw rubber (styrene-butadiene copolymer), a filler, an organosilane coupling agent, a process oil, a zinc white, stearic acid, an antioxidant, an antiaging agent, wax and an accelerator were mixed and mulled by using a banbury mixer equipped with a temperature controlling apparatus. In this case, the temperature of the mulling apparatus was controlled to 140° C., and a first compound mixture was obtained at a discharge temperature of 140° C. to 150° C. In the second stage mulling, the first compound mixture was cooled to room temperature, and the first compound mixture, sulfur and a vulcanization accelerator were added to the mulling apparatus and mixed at a temperature of 60° C. or less to obtain a second compound mixture. Then, a curing process was performed at 180° C. for t90+10 minutes to manufacture a rubber specimen.

2) Tensile Properties

The tensile properties were measured by manufacturing each specimen for test and measuring tensile strength when breaking and tensile stress when elongating by 300% (300% modulus) of each specimen according to an ASTM 412 tensile test method. Particularly, tensile properties were measured by using a Universal Test machin 4204 tensile tester (Instron Co., Ltd.) at room temperature at a rate of 50 cm/min.

3) Viscoelasticity Properties

Viscoelasticity properties were obtained by measuring tan δ while changing deformation at each measurement temperature (−60° C. to 60° C.) and a frequency of 10 Hz with a twist mode by using a dynamic mechanical analyzer (TA Co., Ltd.). Payne effect was shown by a difference between a minimum value and a maximum value at the deformation of 0.28% to 40%. If tan δ at a low temperature of 0° C. is high, it means that wet skid resistance is good, and if tan δ at a high temperature of 60° C. is low, it means that hysteresis loss is small and low rolling resistance (fuel consumption ratio) is excellent.

TABLE 3 Comparative Example Example Division 1 2 1 2 Tensile 300% modulus 213 193 160 170 properties (kgf/cm²) Tensile strength 132 130 100 110 (kgf/cm²) Viscoelasticity tan δ @0° C. 0.967 0.970 0.647 0.782 tan δ @60° C. 0.101 0.108 0.133 0.118

As shown in Table 3, the modified conjugated diene-based polymers according to the present invention were found to have excellent tensile properties and markedly improved viscoelasticity properties when compared to Comparative Example 1 in which modification reaction was not performed and Comparative Example 2 in which modification reaction was performed using a modifier not including a glycidol group.

From the results, according to the present invention, the preparation of a modified conjugated diene-based polymer making excellent interaction between a polymer and an inorganic filler is capable by including a functional group derived from a modifier making excellent interaction with an inorganic filler when mixed therewith, at one terminal of the polymer, and thus, the modified conjugated diene-based polymer thus prepared was found to have good processability and excellent tensile strength, abrasion resistance and wet skit resistance. 

1. A modified conjugated diene-based polymer comprising a repeating unit derived from a conjugated diene-based monomer, and comprising a functional group derived from a modifier which includes a compound represented by the following Formula 1 at one terminal:

in Formula 1, X¹ and X² are each independently an N atom or CR⁷, where one or more of X¹ and X² are required to be N atoms, R¹ to R⁴ are each independently a divalent hydrocarbon group of 1 to 30 carbon atoms, or a heteroalkylene group of 1 to 30 carbon atoms, which comprises one or more heteroatoms selected from the group consisting of N, O and S atoms, R⁵ and R⁶ are each independently a monovalent hydrocarbon group of 1 to 30 carbon atoms, a heteroalkyl group of 1 to 30 carbon atoms, which comprises one or more heteroatoms selected from the group consisting of N, O and S atoms, or a heterocycle of 1 to 30 carbon atoms, which comprises one or more heteroatoms selected from the group consisting of N, O and S atoms, and R⁷ is a hydrogen atom, a monovalent hydrocarbon group of 1 to 30 carbon atoms, a heteroalkyl group of 1 to 30 carbon atoms, which comprises one or more heteroatoms selected from the group consisting of N, O and S atoms, or a heterocycle of 1 to 30 carbon atoms, which comprises one or more heteroatoms selected from the group consisting of N, O and S atoms.
 2. A modified conjugated diene-based polymer comprising a repeating unit derived from a conjugated diene-based monomer, comprising a compound represented by the following Formula 1 at one terminal, and comprising a functional group derived from a modification initiator which comprises a compound represented by the following Formula 2 at the other terminal:

in Formula 1, X¹ and X² are each independently an N atom or CR⁷, where one or more of X¹ and X² are required to be N atoms, R¹ to R⁴ are each independently a divalent hydrocarbon group of 1 to 30 carbon atoms, or a heteroalkylene group of 1 to 30 carbon atoms, which comprises one or more heteroatoms selected from the group consisting of N, O and S atoms, R⁵ and R⁶ are each independently a monovalent hydrocarbon group of 1 to 30 carbon atoms, a heteroalkyl group of 1 to 30 carbon atoms, which comprises one or more heteroatoms selected from the group consisting of N, O and S atoms, or a heterocycle of 1 to 30 carbon atoms, which comprises one or more heteroatoms selected from the group consisting of N, O and S atoms, and R⁷ is a hydrogen atom, a monovalent hydrocarbon group of 1 to 30 carbon atoms, a heteroalkyl group of 1 to 30 carbon atoms, which comprises one or more heteroatoms selected from the group consisting of N, O and S atoms, or a heterocycle of 1 to 30 carbon atoms, which comprises one or more heteroatoms selected from the group consisting of N, O and S atoms,

in Formula 2, R⁸ and R⁹ are each independently one selected from the group consisting of an alkyl group of 1 to 20 carbon atoms, a cycloalkyl group of 3 to 20 carbon atoms, and an aralkyl group of 5 to 20 carbon atoms, or R⁸ and R⁹ are combined with each other to form a saturated or unsaturated cyclic structure of 5 to 20 carbon atoms together with an adjacent N atoms, where if R⁸ and R⁹ form a cyclic structure, a branched structure may be obtained, R¹⁰ is a single bond, an alkylene group of 1 to 20 carbon atoms, or one linker selected from the group consisting of the following Formula 3 to Formula 5, and M is an alkali metal:


3. The modified conjugated diene-based polymer of claim 1, wherein the modified conjugated diene-based polymer further comprises a repeating unit derived from an aromatic vinyl monomer.
 4. The modified conjugated diene-based polymer of claim 1, wherein in Formula 1, X¹ and X² are N atoms, R¹ to R⁴ are each independently a divalent hydrocarbon group of 1 to 10 carbon atoms, and R⁵ and R⁶ are each independently a monovalent hydrocarbon group of 1 to 10 carbon atoms.
 5. The modified conjugated diene-based polymer of claim 1, wherein the compound represented by Formula 1 is represented by the following Formula 1-1 or 1-2:

in Formulae 1-1 and 1-2, Me is a methyl group and Et is an ethyl group.
 6. The modified conjugated diene-based polymer of claim 1, wherein the modified conjugated diene-based polymer has a number average molecular weight (Mn) of 10,000 g/mol to 2,000,000 g/mol.
 7. The modified conjugated diene-based polymer of claim 1, wherein the modified conjugated diene-based polymer has molecular weight distribution (Mw/Mn) of 1 to
 5. 8. A method for preparing a modified conjugated diene-based polymer, the method comprising: polymerizing conjugated diene-based monomers, or an aromatic vinyl-based monomer and a conjugated diene-based monomer, in a hydrocarbon solvent which comprises an organometal compound, to prepare an active polymer which is coupled with an organometal (S1); and reacting the active polymer and a modifier which comprises a compound represented by the following Formula 1 (S2):

in Formula 1, X¹ and X² are each independently an N atom or CR⁷, where one or more of X¹ and X² are required to be N atoms, R¹ to R⁴ are each independently a divalent hydrocarbon group of 1 to 30 carbon atoms, or a heteroalkylene group of 1 to 30 carbon atoms, which comprises one or more heteroatoms selected from the group consisting of N, O and S atoms, R⁵ and R⁶ are each independently a monovalent hydrocarbon group of 1 to 30 carbon atoms, a heteroalkyl group of 1 to 30 carbon atoms, which comprises one or more heteroatoms selected from the group consisting of N, O and S atoms, or a heterocycle of 1 to 30 carbon atoms, which comprises one or more heteroatoms selected from the group consisting of N, O and S atoms, and R⁷ is a hydrogen atom, a monovalent hydrocarbon group of 1 to 30 carbon atoms, a heteroalkyl group of 1 to 30 carbon atoms, which comprises one or more heteroatoms selected from the group consisting of N, O and S atoms, or a heterocycle of 1 to 30 carbon atoms, which comprises one or more heteroatoms selected from the group consisting of N, O and S atoms.
 9. The method for preparing a modified conjugated diene-based polymer of claim 8, wherein the organometal compound is used in 0.01 mmol to 10 mmol based on total 100 g of the monomers.
 10. The method for preparing a modified conjugated diene-based polymer of claim 8, wherein the organometal compound is one or more selected from the group consisting of methyllithium, ethyllithium, propyllithium, n-butyllithium, s-butyllithium, t-butyllithium, hexyllithium, n-decyllithium, t-octyllithium, phenyllithium, 1-naphthyl lithium, n-eicosyl lithium, 4-butylphenyl lithium, 4-tolyl lithium, cyclohexyl lithium, 3,5-di-n-heptylcyclohexyl lithium, 4-cyclopentyl lithium, naphthyl sodium, naphthyl potassium, lithium alkoxide, sodium alkoxide, potassium alkoxide, lithium sulfonate, sodium sulfonate, potassium sulfonate, lithium amide, sodium amide, potassium amide, and lithium isopropylamide.
 11. The method for preparing a modified conjugated diene-based polymer of claim 8, wherein the polymerization of step (S1) is performed by comprising a polar additive.
 12. The method for preparing a modified conjugated diene-based polymer of claim 11, wherein the polar additive is one or more selected from the group consisting of tetrahydrofuran, ditetrahydrofurylpropane, diethyl ether, cycloamyl ether, dipropyl ether, ethylene dimethyl ether, diethyl glycol, dimethyl ether, tert-butoxy ethoxy ethane, bis(3-dimethylaminoethyl) ether, (dimethylaminoethyl) ethyl ether, trimethylamine, triethylamine, tripropylamine, and tetramethylethylenediamine.
 13. A modifier comprising a compound represented by the following Formula 1:

in Formula 1, X¹ and X² are each independently an N atom or CR⁷, where one or more of X¹ and X² are required to be N atoms, R¹ to R⁴ are each independently a divalent hydrocarbon group of 1 to 30 carbon atoms, or a heteroalkylene group of 1 to 30 carbon atoms, which comprises one or more heteroatoms selected from the group consisting of N, O and S atoms, R⁵ and R⁶ are each independently a monovalent hydrocarbon group of 1 to 30 carbon atoms, a heteroalkyl group of 1 to 30 carbon atoms, which comprises one or more heteroatoms selected from the group consisting of N, O and S atoms, or a heterocycle of 1 to 30 carbon atoms, which comprises one or more heteroatoms selected from the group consisting of N, O and S atoms, and R⁷ is a hydrogen atom, a monovalent hydrocarbon group of 1 to 30 carbon atoms, a heteroalkyl group of 1 to 30 carbon atoms, which comprises one or more heteroatoms selected from the group consisting of N, O and S atoms, or a heterocycle of 1 to 30 carbon atoms, which comprises one or more heteroatoms selected from the group consisting of N, O and S atoms.
 14. The modified conjugated diene-based polymer of claim 2, wherein the modified conjugated diene-based polymer further comprises a repeating unit derived from an aromatic vinyl monomer.
 15. The modified conjugated diene-based polymer of claim 2, wherein in Formula 1, X¹ and X² are N atoms, R¹ to R⁴ are each independently a divalent hydrocarbon group of 1 to 10 carbon atoms, and R⁵ and R⁶ are each independently a monovalent hydrocarbon group of 1 to 10 carbon atoms.
 16. The modified conjugated diene-based polymer of claim 2, wherein the compound represented by Formula 1 is represented by the following Formula 1-1 or 1-2:

in Formulae 1-1 and 1-2, Me is a methyl group and Et is an ethyl group.
 17. The modified conjugated diene-based polymer of claim 2, wherein the modified conjugated diene-based polymer has a number average molecular weight (Mn) of 10,000 g/mol to 2,000,000 g/mol.
 18. The modified conjugated diene-based polymer of claim 2, wherein the modified conjugated diene-based polymer has molecular weight distribution (Mw/Mn) of 1 to
 5. 